Apparatus for preventing thermal shock to lining of furnace door or cover



Feb. 2, 1960 P. P. SWIFT APPARATUS FOR PREVENTING THERMAL snocx TO LINING OF FURNACE DOOR OR COVER Filed March 2, 1956 INVENTOR. PRENTI-SS P. SWIFT,

W QMQ his Attorney.

APPARATUS FOR PREVENTING THERMAL SHOCK TO LINING OF FURNACE DOOR OR COVER Prentiss P. Swift, Pittsburgh, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Application March 2, 1956, Serial No. 569,060

3 Claims. (Cl. 110-173) This invention relates, as indicated, to an apparatus for preventing thermal shock to the refractory lining of a furnace door or cover and, more particularly, is directed to an auxiliary heater for supplying heat to the refractory lining when the furnace door or cover is moved to its open position to thereby prevent its being cooled and thermal shock incident to such cooling.

Door covers or lids of high temperature heating furnace such as soaking pits, open hearths and other metallurgical furnaces are commonly constructed of or lined with refractory material and are mounted for movement between open and closed positions. In the closed position, the refractory material covers an opening to the interior of the furnace and, being subjected directly to the heat of the furnace, is heated to an incandescent temperature. Upon movement to its open position, the refractory material cools rapidly and its temperature changes over a wide range. in a relatively short period of time. This rapid temperature change due to cooling subjects the refractory material to thermal shock of a nature which is frequently effective to cause cracking at its surface and subsequent spalling off of refractory material and thus operates to shorten the expected life of the door.

One of the principal objects of this invention is to provide an apparatus for preventing cooling of a refractory furnace door upon movement to its open position to thereby prevent thermal shock to the refractory material forming a lining therefor.

Another object of the invention is to provide an auxiliary heater for supplying heat to the refractory material or lining of a furnace door or cover upon movement to its open position.

A still further object of the invention is to provide a heating furnace having a refractory door or cover movable between open and closed positions with an auxiliary heater which is so related to the open position of the door or cover that it is operative to supply heat to and thereby prevent cooling of the refractory when the door or cover is moved to its open position.

Other objects and advantages of the invention will become apparent from the following description.

In the drawings, there is shown a preferred example of the invention as applied to a soaking pit and cover therefor which are illustrated somewhat diagrammatically. In this showing:

Figure 1 is a plan view of a soaking pit and cover therefor which are provided with an auxiliary heater constructed in accordance with the principles of this invention for heating the cover when moved to its open position;

Figure 2 is a vertical sectional view of the soaking pit and cover taken substantially along the lines II-II of Figure l; and

Figures 3 and 4 are fragmentary sectional views taken respectively along the lines III-III and IV-IV of Figure 1.

T'ited States Patent "ice The furnace in the drawings is a diagrammatic illustration of a soaking pit comprised of a refractory base 1 and walls 2 which define a chamber 3 in which steel ingots to be heated are received. A cover 4 of refractory material closes the upper end of the chamber 3 during heating operation of the furnace and in practice has conventional sealing provisions (not shown) about its periphery with the upper edges of the walls 2. A trolley carriage 5 is provided for moving the cover 4 from the closed position shown in solid lines in Figures 1 and 2 to an open position at one side of the chamber 3 as indicated by broken lines in Figure 1. The carriage 5 has flanged wheels 6 mounting it for movement along track rails 7 on a supporting platform 8. The platform 8 and the upper edges of the walls 2 in effect provide a furnace wall having an opening 9 which forms a charging opening for the chamber 3 and which is adapted to be closed by the cover 4. The carriage 5 has been illustrated diagrammatically and it will be understood that it is provided with the usual conventional mechanism (not shown) for raising and lowering the cover 4 into and out of sealing engagement with the soaking pit walls 2 and for supporting it during movement between open and closed positions. The cover 4, as in conventional practice, includes a supporting frame (not shown) for the refractory material of which it is formed.

In accordance with the principles of this invention, the soaking pit is provided with a heater or fuel burner, designated as a whole by the numeral 10, which is mounted exteriorly of the furnace on the platform 8 at one side'of the chamber 3 and in a position directly underneath the cover 4 when moved'to the openposition designated by the broken lines in Figure 1. While it is to be understood that other conventional types of heaters may be used and are contemplated, the heater 10 is preferably' a gaseous fuel burner which is fed a combustible gas by a supply conduit 11. Connection of the burner 10 with the supply conduit 11 is controlled by a two-way valve 12 of any suitable conventional construction having on and off positions and which is provided with a bias (not shown) for movement to its olf position. A control lever 13 is provided for operating the valve 12 and projects upwardly into the path of movement of the cover 4 to its open position for actuation thereby in a manner to-be described.

The valve 12 controls the supply of fuel gas to a header conduit 14 extending transversely of the path of movement of the cover 4 over the platform 8. The header conduit 14 is connected with and supplies fuel gas to a plurality of parallel burner pipes 15 arranged at spaced intervals transversely of the platform 8. Each of the burner pipes 15 has a plurality of burner open-' ings 16 through which fuel gas is projected upwardly against the undersurface of the cover 4 when in its open position and, in being so projected, the fuel gas is mixed with the surrounding atmospheric air to form acombustible mixture. The upper surface of the platform 3 is provided with slots or recesses 17 in which the header and burner pipes 14 and 15 are received and thus located in a position below the upper surface 18 of the platform 8 as best shown in Figure 4. In this manner, the burner 10 is positioned below the cover 4 and will not interfere with its movement to its open position.

As best shown in Figure 3, the actuating lever 13 for the valve 12 projects upwardly into the path of movement of the cover 4 to its open position. With the lever 13 occupying the position shown in solid lines in Figure 3, the valve 12 is in its off position disconnecting the burner 10 with respect to the supply conduit 11. In operation, the valve lever 13 is actuated to the position shown in dotted lines in Figure 3 by the cover 4 during its final a 3 movement to open position by movement of the carriage 5 along the track rails 7. This movement of the lever 13 actuates the valve 12 to its on position thereby connecting the burner pipes 14 and 15 with the gas supply pipe 11. The combustible mixture of gas and air moving upwardly from the opening 16 as described above will be ignited by the refractory material in the cover 4 which will be at an incandescent temperature when moved to its open position. If desired, pilot burners (not shown) may be provided for insuring ignition of the fuel gas being projected through the openings 16. The burning gaseous mixture projected against the overlying cover 4 will maintain the refractory material therein at an elevated temperature to thereby prevent its being subjected to thermal shock. Upon return movement of the cover 4 to its closed position over the soaking pit chamber 3, the valve actuating lever 13 is automatically returned to the position shown in solid lines in Figure 3 by the bias (not shown) which actuates the valve 12 to its ofi position. Movement of the cover 4 to its closed position is thus effective to discontinue heating operation of the heater 10.

While the above furnishes an embodiment of the invention as applied to soaking pits and covers therefor, it will be understood that the principles of the invention with respect to the provision of the heater and its operation are applicable to refractory closure doors or covers for other types of furnaces and that such uses of the invention are contemplated. It will also be understood that the showing of the valve control lever 13 is in a sense diagrammatic and that other conventional mechanisms are contemplated for controlling the operation of the burner 10 as described in response to opening and closing movements of a furnace door. Accordingly, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In a heating furnace having a charging opening, a heater mounted exteriorly of said furnace, a refractory 4 door mounted on said furnace for movement from a closed position over said opening to an open position over said heater, means controlling the operation of said heater, and means responsive to movement of said door to said open position for actuating said controlling means to render said heater operative to heat said door.

2. In a heating furnace having a furnace wall with a charging opening therein, a refractory door mounted for movement along said wall from a closed position over said opening to an open position spaced from said opening, a fuel gas burner mounted on said wall in a position under said door when moved to its said open position, a valve controlling the admission of fuel gas to said burner, and means for actuating said valve to admit fuel gas to said burner in response to movement of said door to said open position.

3. In a heating furnace having a wall with a charging opening therein, a door closure including a refractory lining mounted on said wall for movement from a closed position over said opening to an open position spaced from said opening, a heater mounted on said wall in a position opposite said refractory lining when said door is moved to said open position, and means controlling the operation of said heater including means for operating it to heat said lining in response to movement of said door to said open position.

References Cited in the file of this patent UNITED STATES PATENTS 1,807,112 Werner May 26, 1931 2,095,979 Hamlink Oct. 19, 1937 2,189,280 Croft Feb. 6, 1940 2,386,565 Nissim Oct. 9, 1945 2,595,243 Gordon May 6, 1952 2,595,991 Sweeney May 6, 1952 2,714,650 Werner Aug. 2, 1955 FOREIGN PATENTS 493,284 Great Britain Sept. 30, 1938 

